LibWeb: Accept a JS::Value for size in enqueue_value instead of a double

This matches what the spec does, and consolidates all of the size-
related errors in one spot instead of distributing them throughout the
various uses of enqueue_value_with_size()

Userland/Libraries/LibWeb/Streams/AbstractOperations.cpp

@@ -453,7 +453,7 @@ WebIDL::ExceptionOr<void> readable_stream_default_controller_enqueue(ReadableStr
         }
 
         // 3. Let chunkSize be result.[[Value]].
-        auto chunk_size = TRY(result.release_value().release_value().to_double(vm));
+        auto chunk_size = result.release_value().release_value();
 
         // 4. Let enqueueResult be EnqueueValueWithSize(controller, chunk, chunkSize).
         auto enqueue_result = enqueue_value_with_size(controller, chunk, chunk_size);
@@ -1489,7 +1489,7 @@ void writable_stream_default_controller_clear_algorithms(WritableStreamDefaultCo
 WebIDL::ExceptionOr<void> writable_stream_default_controller_close(WritableStreamDefaultController& controller)
 {
     // 1. Perform ! EnqueueValueWithSize(controller, close sentinel, 0).
-    TRY(enqueue_value_with_size(controller, create_close_sentinel(), 0.0));
+    TRY(enqueue_value_with_size(controller, create_close_sentinel(), JS::Value(0.0)));
 
     // 2. Perform ! WritableStreamDefaultControllerAdvanceQueueIfNeeded(controller).
     TRY(writable_stream_default_controller_advance_queue_if_needed(controller));
@@ -1626,6 +1626,25 @@ WebIDL::ExceptionOr<void> writable_stream_default_controller_process_write(Writa
     return {};
 }
 
+// https://streams.spec.whatwg.org/#is-non-negative-number
+bool is_non_negative_number(JS::Value value)
+{
+    // 1. If Type(v) is not Number, return false.
+    if (!value.is_number())
+        return false;
+
+    // 2. If v is NaN, return false.
+    if (value.is_nan())
+        return false;
+
+    // 3. If v < 0, return false.
+    if (value.as_double() < 0.0)
+        return false;
+
+    // 4. Return true.
+    return true;
+}
+
 // https://streams.spec.whatwg.org/#close-sentinel
 // Non-standard function that implements the "close sentinel" value.
 JS::Value create_close_sentinel()

Userland/Libraries/LibWeb/Streams/AbstractOperations.h

@@ -89,6 +89,8 @@ double writable_stream_default_controller_get_desired_size(WritableStreamDefault
 WebIDL::ExceptionOr<void> writable_stream_default_controller_process_close(WritableStreamDefaultController&);
 WebIDL::ExceptionOr<void> writable_stream_default_controller_process_write(WritableStreamDefaultController&, JS::Value chunk);
 
+bool is_non_negative_number(JS::Value);
+
 JS::Value create_close_sentinel();
 bool is_close_sentinel(JS::Value);
 JS::ThrowCompletionOr<JS::Handle<WebIDL::CallbackType>> property_to_callback(JS::VM& vm, JS::Value value, JS::PropertyKey const& property_key);
@@ -125,13 +127,15 @@ JS::Value dequeue_value(T& container)
 
 // https://streams.spec.whatwg.org/#enqueue-value-with-size
 template<typename T>
-WebIDL::ExceptionOr<void> enqueue_value_with_size(T& container, JS::Value value, double size)
+WebIDL::ExceptionOr<void> enqueue_value_with_size(T& container, JS::Value value, JS::Value size_value)
 {
     // 1. Assert: container has [[queue]] and [[queueTotalSize]] internal slots.
 
     // 2. If ! IsNonNegativeNumber(size) is false, throw a RangeError exception.
-    if (size < 0.0)
+    if (!is_non_negative_number(size_value))
-        return WebIDL::SimpleException { WebIDL::SimpleExceptionType::RangeError, "Chunk has negative size"sv };
+        return WebIDL::SimpleException { WebIDL::SimpleExceptionType::RangeError, "Chunk has non-positive size"sv };
+
+    auto size = size_value.as_double();
 
     // 3. If size is +∞, throw a RangeError exception.
     if (size == HUGE_VAL)